Storyboy, thanks a lot, it looks very effective. For now I am testing threads, one silk, one nylon, both ca 1mm thick. I can tension the thread by adjusting the player feet to widen the distance to the pulley. The platter starts ok and I do notice sound improvements, but I have not managed to get the speed right. Since it had been used with the standard rubber belt, the SDS was tuned to 72 volts / 60.00 hz (for 33 rpm). With the thread it remained too slow even when I turned it up all the way to 66.00 hz, which is the top level for 33 rpm. I tried switching to 45 rpm, but then it went too fast, and remained too fast even when turning the hz fully down. My pulley has two groves, one small-diameter at the top which is correct for the rubber belt, and one larger below it. I tried changing to the larger grove, but this made the speed even faster and did not solve my problem. My experiences were similar with the two threads. I also felt that the speed was a bit fluctuating, but I must get it fairly right before I can tell. Advice welcome.